Polymer materials containing dispersed carbon nanotubes

ABSTRACT

The invention relates to a polymer material comprising 99 to 20 parts by weight of polymer(s), 0.1 to 80 parts by weight of carbon nanotubes, and 0.05 to 80 parts by weight of at least one type of dispersant selected from A-B-C, B-C and/or C-B-C block copolymers, wherein each block is bonded to the other by means of a covalent bond, C is a chemical and/or physical interaction with the polymer material and in preferably is miscible therwith, B is not miscible with the polymer material and with the block B and the glass transition temperature thereof. T g  is less than the polymer material use temperature, A is not miscible with the polymer material and with the blocks B and the block C and the T g  or the fusion temperature Tf is greater than the T g  of B.

This U.S. patent application is a National Stage of the PCT applicationof PCT/FR2006/000708 filed Mar. 31, 2006.

TECHNICAL FIELD

The present invention relates to polymer materials containing carbonnanotubes.

Owing to their very high mechanical properties and the very highlength/diameter ratio, carbon nanotubes (CNTs) are materials offeringsubstantial advantages as reinforcing agents. In addition, theirelectrical and thermal properties also allow them to be used to modifythe conducting properties of the materials into which they areincorporated.

Carbon nanotubes are made up from graphite sheets wound up andterminated by hemispheres consisting of pentagons and hexagons having astructure similar to fullerenes.

Nanotubes are known to be composed either of a single sheet, in whichcase they are called SWNTs (single-walled nanotubes), or made up fromseveral concentric sheets, when they are called MWNTs (multi-wallednanotubes), SWNTs being in general more difficult to manufacture thanMWNTs.

PRIOR ART

EP 692 136 has disclosed polymer compositions containing up to 20% byweight of CNT. These compositions, which are thermoplastic orthermosetting, are prepared by melt blending the polymers with the CNTs.However, it has been found that the dispersion of the CNTs within thepolymer matrix is not uniform and the expected mechanical and/orelectrical properties are insufficient.

There is an unsatisfied demand for improving the way in which the CNTsare dispersed within the polymer materials into which they areincorporated, so as to obtain more uniform materials.

EP 1 359 121 and EP 1 359 169 propose to improve the dispersion of CNTsin polymer matrices by functionalizing the CNTs.

SUMMARY OF THE INVENTION

The present invention relates to a polymer material comprising:

-   -   99 to 20 parts by weight of polymer(s);    -   0.1 to 80 parts by weight of carbon nanotubes; and    -   0.05 to 80 parts by weight of at least one dispersant chosen        from A/B/C, B/C and/or C/B/C block copolymers in which:        -   each block is linked to another by means of a covalent bond            or an intermediate molecule linked to one of the blocks via            a covalent bond and to the other block via another covalent            bond,        -   C provides an interaction of the chemical and/or physical            type with the polymer material and is preferably miscible            with the said material,        -   B is not miscible with the polymer material and with the            block C, and its glass transition temperature T_(g) is below            the usage temperature of the polymer material and        -   A is not miscible with the polymer material, the block B and            the block C, and its T_(g) or its melting point T_(m) is            above the T_(g) of B.

The term “polymer(s)” is understood throughout the following to mean anycomposition based on one or more polymers of any type: thermoplastic orthermosetting, rigid or elastomeric, amorphous, crystalline and/orsemicrystalline, homopolymer, copolymer, etc.; these compositions may beblends of one or more different polymers, with various additives,adjuvants and/or fillers conventionally added to polymers, such asstabilizers, plasticizers, polymerization catalysts, dyes, pigments,lubricants, fire retardants, reinforcements and/or fillers,polymerization solvents, etc.

The polymers may be polymers containing functional groups of the epoxideand/or glycidyl or ether type, of the monocarboxylic, dicarboxylic orpolycarboxylic acid type, whether saturated or unsaturated, whetheraromatic or non-aromatic, or an acid-derived functional group, such asan anhydride, ester, amide and/or imide, of the vinyl, vinylaromatictype, etc., it being understood that the definitions of the polymersgiven below may be redundant in so far as certain polymers containseveral of the functional groups listed above.

Thermosetting polymers are in general defined as being formed frompolymer chains of variable length linked together by covalent bonds soas to form a three-dimensional network.

As an example, mention may be made of cyanoacrylates, bismaleimides andepoxy resins crosslinked by a hardener or cure agent.

Among cyanoacrylates, mention may be made of 2-cyanoacrylic esters,which are thermosetting materials obtained by the polymerization of themonomer CH₂═C(CN)COOR with various possible groups R (without the needto add a hardener).

Thermosetting formulations of the bismaleimide type are, for example:methylenedianiline+benzophenone dianhydride+nadic imide;methylenedianiline+benzophenone dianhydride+phenylacetylene;methylenedianiline+maleic anhydride+maleimide.

Advantageously, the thermosetting material derives from the reaction ofa thermosetting epoxy resin and a hardener. It is also defined as beingany product resulting from the reaction of an oligomer carrying oxiranefunctional groups with a hardener. What is obtained from the reactionsinvolved during the reaction of these epoxy resins is a crosslinkedmaterial corresponding to a three-dimensional network of greater orlesser density depending on the base characteristics of the resins andhardeners employed.

The expression “epoxy-type polymer” is understood to mean any organiccompound possessing at least two oxirane-type functional groups, whichcan polymerize by ring opening. The term “epoxy polymers” denotes allthe usual epoxy resins that are liquid at room temperature (23° C.) orat a higher temperature. These epoxy resins may on the one hand bemonomeric or polymeric and, on the other hand, aliphatic,cycloaliphatic, heterocyclic or aromatic. As examples of such epoxyresins, mention may be made of the diglycidyl ether of resorcinol, thediglycidyl ether of bisphenol A, triglycidyl-p-aminophenol, thediglycidyl ether of bromobisphenol F, the triglycidyl ether ofm-aminophenol, tetraglycidyl methylene dianiline, the triglycidyl etherof (trihydroxyphenyl)methane, the polyglycidyl ethers of novolacphenol-formaldehyde, the polyglycidyl ethers of novolac orthocresol andthe tetraglycidyl ethers of tetraphenylethane. Blends of at least two ofthese resins may also be used.

Epoxy resins possessing at least 1.5 oxirane functional groups permolecule, and more particular epoxy resins containing between 2 and 4oxirane functional groups per molecule, are preferred. Epoxy resinspossessing at least one aromatic ring, such as the diglycidyl ethers ofbisphenol A, are also preferred.

With regard to the hardener, it is general practice to use as hardenersthe epoxy resin hardeners that react at room temperature or attemperatures above room temperature. As non-limiting examples, mentionmay be made of:

-   -   acid anhydrides, among which is succinic anhydride;    -   aromatic or aliphatic polyamines, among which are        diaminodiphenyl sulphone (DDS), methylene dianiline and        4,4′-methylenebis(3-chloro-2,6-diethylaniline) (MCDEA);    -   dicyandiamide and its derivatives;    -   imidazoles;    -   polycarboxylic acids; and    -   polyphenols.

With regard to polymers having epoxide and/or glycidyl functional groupsmention may also be made of copolymers of ethylene with at least oneunsaturated epoxide, which may be obtained by the copolymerization ofethylene with one or more unsaturated epoxides or by grafting theunsaturated epoxide(s) onto polyethylene. The grafting may be carriedout in a solvent phase or on polyethylene in the melt in the presence ofa peroxide. These grafting techniques are known per se. As regards thecopolymerization of ethylene with an unsaturated epoxide, radicalpolymerization processes normally operating at pressures between 200 and2 500 bar may be used.

The term “polyethylene” is understood to mean ethylene homopolymers andcopolymers.

By way of ethylene comonomers, mention may be made of:

-   -   alpha-olefins, advantageously those having from 3 to 30 carbon        atoms; by way of examples of alpha-olefins, mention may be made        of propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene,        4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene,        1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene,        1-eicocene, 1-dococene, 1-tetracocene, 1-hexacocene,        1-octacocene and 1-triacontene; these alpha-olefins may be used        separately or as a mixture of two or more of them;    -   esters of unsaturated carboxylic acids, such as, for example,        alkyl (meth)acrylates, the alkyls possibly having up to 24        carbon atoms; examples of alkyl acrylates or methacrylates are        especially methyl methacrylate, ethyl acrylate, n-butyl        acrylate, isobutyl acrylate and 2-ethylhexyl acrylate;    -   vinyl esters of saturated carboxylic acids, such as, for        example, vinyl acetate or vinyl propionate;    -   dienes such as, for example, 1,4-hexadiene.

The polyethylene may include several of the above comonomers.

Advantageously, the polyethylene, which may be a blend of severalpolymers, comprises at least 50 mol % and preferably 75 mol % ofethylene and its density may be between 0.86 and 0.98 g/cm³. The MFI(Melt Flow Index at 190° C./2.16 kg) is advantageously between 20 and1000 g/10 min.

By way of example of polyethylenes, mention may be made of:

-   -   low-density polyethylene (LDPE);    -   high-density polyethylene (HDPE);    -   linear low-density polyethylene (LLDPE);    -   very low-density polyethylene (VLDPE);    -   polyethylene obtained by metallocene catalysis, that is to say        polymers obtained by the copolymerization of ethylene and of an        alpha-olefin such as propylene, butene, hexene or octene in the        presence of a single-site catalyst generally consisting of a        zirconium or titanium atom and of two alkyl cyclic molecules        linked to the metal. More specifically, the metallocene        catalysts are usually composed of two cyclopentadiene rings        linked to the metal. These catalysts are frequently used with        aluminoxanes as cocatalysts or activators, preferably        methylaluminoxane (MAO). Hafnium may also be used as the metal        to which the cyclopentadiene is fixed. Other metallocenes may        include transition metals of IV A, V A and VI A. Metals from the        series of lanthamides may also be used;    -   EPR (ethylene-propylene-rubber) elastomers;    -   EPDM (ethylene-propylene-diene) elastomers;    -   blends of polyethylene with an EPR or an EPDM; and    -   ethylene-alkyl (meth)acrylate copolymers possibly containing up        to 60%, and preferably 2 to 40%, by weight of (meth)acrylate.

Grafting is an operation known per se.

By way of example of unsaturated epoxides, mention may be made of:

-   -   aliphatic glycidyl esters and ethers, such as allyl glycidyl        ether, vinyl glycidyl ether, glycidyl maleate, glycidyl        itaconate, glycidyl acrylate and glycidyl methacrylate; and    -   alicyclic glycidyl esters and ethers, such as 2-cyclohex-1-ene        glycidyl ether, diglycidyl cyclohexene-4-5-dicarboxylate,        glycidyl cyclohexene-4-carboxylate, glycidyl        2-methyl-5-norbornene-2-carboxylate and diglycidyl        endo-cis-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylate.

The polymers having epoxide and/or glycidyl functional groups alsocomprise the polymers listed above, some of the monomer or monomershaving epoxide and/or glycidyl functional groups of which is replacedwith unsaturated monomers that can be copolymerized with the monomershaving epoxide and/or glycidyl functional groups, and especially(meth)acrylic esters, such as for example ethylene/methylmethacrylate/glycidyl (meth)acrylate terpolymers.

Thus, the polymer having epoxide and/or glycidyl functional groups mayadvantageously be an ethylene/alkyl (meth)acrylate/unsaturated epoxidecopolymer. Advantageously, it may contain up to 40%, preferably 5 to40%, by weight of alkyl (meth)acrylate and up to 10%, preferably 0.1 to8%, by weight of unsaturated epoxide. Advantageously, the epoxide isglycidyl (meth)acrylate.

Advantageously, the alkyl (meth)acrylate is chosen from methyl(meth)acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate and2-ethylhexyl acrylate. The amount of alkyl (meth)acrylate isadvantageously from 20 to 35%. The MFI is advantageously between 5 and100 (in g/10 min. at 190° C./2.16 kg) and the melting point is between60 and 110° C. This copolymer may be obtained from the radicalpolymerization of the monomers.

Among commercial polymers having epoxide functional groups, mention mayfor example be made of LOTADER® GMA (an ethylene/methylmethacrylate/glycidyl methacrylate terpolymer) sold by Arkema.

With regard to polymers having acid and/or acid anhydride functionalgroups, mention may be made of polyolefins grafted by an unsaturatedcarboxylic acid anhydride, and also copolymers of an olefin with anunsaturated carboxylic acid anhydride obtained for example by radicalpolymerization, and more particularly those based on ethylene, asdefined above.

The unsaturated carboxylic acid anhydride may be chosen from maleic,itaconic, citraconic, allylsuccinic, cyclohex-4-ene-1,2-dicarboxylic,bicyclo-[2.2.1]hept-5-ene-2,3-dicarboxylic,4-methylenecyclohex-4-ene-1,2-dicarboxylic, andx-methylbicyclo[2.2.1]hept-5-ene-2,2-dicarboxylic anhydrides.Advantageously, maleic anhydride is used. It would not be outside thescope of the invention to replace all or part of the anhydride with oneor more unsaturated carboxylic acids such as, for example, (meth)acrylicacid.

With regard to copolymers of ethylene with an unsaturated carboxylicacid anhydride, that is to say those in which the unsaturated carboxylicacid anhydride is not grafted, these are copolymers of ethylene with anunsaturated carboxylic acid anhydride and optionally with anothermonomer that may be chosen from the comonomers mentioned above for theethylene copolymers intended to be grafted.

Advantageously, ethylene/maleic anhydride and ethylene/alkyl(meth)acrylate(s)/maleic anhydride copolymers are used. These copolymerscomprise in general 0.2 to 10% by weight of maleic anhydride and 0 to40%, preferably 5 to 40%, by weight of alkyl (meth)acrylate. Their MFIis between 20 and 100 (190° C.-2.16 kg). The alkyl (meth)acrylates havealready been described above. The melting point is between 80 and 120°C.

Such copolymers are commercially available and are prepared by radicalpolymerization at a pressure that may be between 200 and 2500 bar, thecopolymers being sold in granule form. They may be powdered, for exampleby microgranulation using the underwater cutting technique of thecompany GAL4 (Virginia, USA), or by cryogenic grinding.

With regard to polymers having acid-derived functional groups of theester type, mention may be made of polymers of the (alkyl)acrylate typeor acrylic polymers, homopolymers and copolymers of one or more alkyl(alkyl)acrylates, which are described in particular in Kirk Othmer,Encyclopedia of Chemical Technology, 4th Edition, Vol. 1, pages 292-293and Vol. 16, pages 475-478. Mention may also be made of copolymers ofone or more alkyl (alkyl)acrylates and of at least one monomer chosenfrom acrylonitrile, butadiene, styrene and isoprene, provided that theproportion of alkyl (alkyl)acrylates is at least 50 mol %.

With regard to polymers having acid-derived functional groups of theester type, mention may also be made of polymers containing unitsderived from one or more vinyl esters of saturated carboxylic acids,such as for example vinyl acetate and vinyl propionate. For example,ethylene and vinyl acetate copolymers may be mentioned, especially thosesold under the names EVATANE®, ELVAX® and ULTRATHENE®.

With regard to polymers having amide functional groups, mention may bemade of polymers resulting from the condensation:

-   -   of one or more amino acids, such as aminocaproic,        7-aminoheptanoic, 11-aminoundecanoic (PA-11) and        12-aminododecanoic (PA-12) acids, or of one or more lactams,        such as caprolactam (PA-6), oenantholactam and lauryllactam;    -   of one or more salts or mixtures of diamines, such as        hexamethylenediamine, dodecamethylenediamine,        metaxylylenediamine, bis(p-aminocyclohexyl)methane and        trimethylhexamethylenediamine with diacids, such as isophthalic,        terephthalic, adipic, azelaic, suberic, sebacic and        dodecanedicarboxylic acids;    -   or of mixtures of certain of these monomers, resulting in        copolyamides, for example PA-6/12 by the condensation of        caprolactam and lauryllactam.

As examples of aliphatic polyamides resulting from the condensation ofan aliphatic diamine having 6 to 12 carbon atoms and of an aliphaticdiacid having 9 to 12 carbon atoms, mention may be made of:

-   -   PA-6, 12 resulting from the condensation of hexamethylenediamine        and 1,12-dodecanedioic acid.

As examples of aliphatic polyamides resulting from the condensation ofan aliphatic diamine having 6 to 12 carbon atoms and an aliphatic diacidhaving 9 to 12 carbon atoms, and amino acids, mention may be made of:

-   -   PA-6/6, 6/12 resulting from the condensation of caprolactam and        hexamethylenediamine and adipic acid and lauryllactam.

The polymer having amide functional groups may be plasticized. Asregards plasticizers, these are generally chosen from benzenesulphonamide derivatives, such as n-butylbenzene sulphonamide (BBSA),ethyltoluene sulphonamide or N-cyclohexyl toluene sulphonamide; estersof hydroxybenzoic acids, such as 2-ethylhexyl parahydroxybenzoate and2-decylhexyl parahydroxybenzoate; esters or ethers of tetrahydrofurfurylalcohol, such as oligoethyleneoxytetrahydrofurfuryl alcohol; and estersof citric acid or hydroxy malonic acid, such as oligoethyleneoxymalonate. A particularly preferred plasticizer is n-butylbenzenesulphonamide (BBSA). The plasticizer(s) may be introduced into thepolyamide during polycondensation or subsequently. The proportion ofplasticizer may in general range up to 30% by weight of the polymerhaving amide functional groups.

The polymer having amide functional groups may also be a copolymerhaving polyamide blocks and polyether blocks (PEBA) resulting from thecopolycondensation of polyamide blocks having reactive end groups withpolyether blocks having reactive end groups, such as, inter alia:

-   -   1) polyamide blocks having diamine chain ends with        polyoxyalkylene blocks having dicarboxylic chain ends;    -   2) polyamide blocks having dicarboxylic chain ends with        polyoxyalkylene blocks having diamine chain ends, obtained by        cyanoethylation and hydrogenation of aliphatic dihydroxylated        alpha,omega-polyoxyalkylene blocks called polyetherdiols;    -   3) polyamide blocks having dicarboxylic chain ends with        polyetherdiols, the products obtained being, in this particular        case, polyetheresteramides.

Polyamide blocks having dicarboxylic chain ends derive, for example,from the condensation of polyamide precursors in the presence of achain-stopping dicarboxylic acid.

Polyamide blocks having diamine chain ends derive, for example, from thecondensation of polyamide precursors in the presence of a chain-stoppingdiamine.

The polymers having polyamide blocks and polyether blocks may alsoinclude randomly distributed units. These polymers may be prepared bythe simultaneous reaction of the polyether and the precursors for thepolyamide blocks. For example, it is possible to make a polyether diol,polyamide precursors and a chain-stopping diacid react together. What isobtained is a polymer having essentially polyether blocks and polyamideblocks of very variable length, but also the various reactants that havereacted randomly, which are distributed randomly along the polymerchain.

It is also possible to make a polyether diamine, polyamide precursorsand a chain-stopping diacid react together. What is obtained is apolymer having essentially polyether blocks and polyamide blocks of veryvariable length, but also the various reactants that have reactedrandomly, which are randomly distributed along the polymer chain.

The amount of polyether blocks in these copolymers having polyamideblocks and polyether blocks represents in general 10 to 70% by weight ofthe copolymer.

The polyetherdiol blocks are either used as such and copolycondensedwith polyamide blocks having carboxylic ends or they are aminated inorder to be converted into polyetherdiamines and condensed withpolyamide blocks having carboxylic ends. They may also be blends withpolyamide precursors and a diacid chain stopper in order to makepolymers having polyamide blocks and polyether blocks with unitsdistributed randomly.

Among commercial polymers having amide functional groups, mention may bemade for example of NYLON GRILAMID® and RILSAN®, which are aliphaticpolyamides, and PEBAX® and VESTAMID®, which are PEBAs.

With regard to polyurethanes, these are formed from soft polyetherblocks, which are residues of polyetherdiols, and from hard blocks(polyurethanes), which result from the reaction of at least onediisocyanate with at least one short diol. The chain-extending shortdiol may be chosen from the glycols mentioned above in the descriptionof polyetheresters. The polyurethane blocks and the polyether blocks arelinked via bonds resulting from the reaction of the isocyanatefunctional groups with the OH functional groups of the polyetherdiol.

Mention may also be made of polyester urethanes for example thosecomprising diisocyanates units, units derived from amorphous polyesterdiols, and units derived from a short chain-extending diol. They maycontain plasticizers.

As examples of commercial thermoplastic polyurethanes, mention may bemade of ELASTOLLAN® from Elastogran Bayer.

With regard to polymers having ether functional groups, mention may bemade of polyoxyalkylenes and especially polyoxymethylene (POM),copolymers having poly(propylene oxide-ethylene oxide) blocks andpolyphenylene oxide (PPO).

Mention may also be made of polyalkylene glycols, which are polyethersterminated by hydroxyl functional groups, such as polyethylene glycol(PEG), polypropylene glycol, polytetramethylene glycol (PTMG), and alsopolyetheresters, which are copolymers having polyester blocks andpolyether blocks. They are formed from soft polyether blocks, which arethe residues of polyether diols, and from hard segments (polyesterblocks), which result from the reaction of at least one dicarboxylicacid with at least one short chain-extending diol unit. The polyesterblocks and the polyether blocks are linked via ester links resultingfrom the reaction of the acid functional groups of the acid with the OHfunctional groups of the polyether diol. The short chain-extending diolmay be chosen from the group consisting of neopentyl glycol,cyclohexanedimethanol and aliphatic glycols of formula HO(CH₂)_(n)OH inwhich n is an integer ranging from 2 to 10. Advantageously, the diacidsare aromatic dicarboxylic acids having 8 to 14 carbon atoms. Up to 50mol % of the aromatic dicarboxylic acid may be replaced with at leastone other aromatic dicarboxylic acid having 8 to 14 carbon atoms and/orup to 20 mol % may be replaced with an aliphatic dicarboxylic acidhaving 2 to 12 carbon atoms.

As examples of aromatic dicarboxylic acids, mention may be made ofterephthalic acid, isophthalic acid, bibenzoic acid, naphthalenedicarboxylic acid, 4,4′-diphenylenedicarboxylic acid,bis(p-carboxyphenyl)methane, ethylene bis(p-benzoic) acid,1,4-tetramethylene bis(p-oxybenzoic) acid, ethylene bis(para-oxybenzoic)acid and 1,3-trimethylene bis(p-oxybenzoic) acid. As examples ofglycols, mention may be made of ethylene glycol, 1,3-trimethyleneglycol, 1,4-tetramethylene glycol, 1,6-hexamethylene glycol,1,3-propylene glycol, 1,8-octamethylene glycol, 1,10-decamethyleneglycol and 1,4-cyclohexanedimethanol. Copolymers having polyester blocksand polyether blocks are for example copolymers having polyether unitsderived from polyether diols, such as PEG, PPG and PTMG, dicarboxylicacid units, such as terephthalic acid, and glycol units (ethanediol or1,4-butanediol). The chain linking of the polyethers and diacids formsthe soft segments, whereas the chain linking of the glycol of thebutanediol with the diacids forms the hard segments of thecopolyetherester. Such copolyetheresters are for example described inthe patents EP 402 883 and EP 405 227. These polyetheresters arethermoplastic elastomers, and they may contain plasticizers.

Among commercial polymers having ether functional groups, mention may bemade for example of ALCON® and HOSTAFORM, which are POMs, ARNITEL®,HYTREL® and LOMOD®, which are block polyetheresters, and PEBAX® andVESTAMID®, which are block polyetheresteramides.

With regard to polymers having vinyl functional groups, these arepolymers, both homopolymers and copolymers, which derive in particularfrom vinyl monomers, such as vinyl chloride. As examples of vinylpolymers, mention may be made of polyvinyl chloride (PVC), chlorinatedPVC, etc.

With regard to polymers having vinylaromatic functional groups, theseare polymers, both homopolymers and copolymers, which derive inparticular from ethylenically unsaturated aromatic monomers, such asstyrene, vinyltoluene, alpha-methylstyrene, 4-methylstyrene,3-methylstyrene, 4-methoxystyrene, 2-hydroxymethylstyrene,4-ethylstyrene, 4-ethoxystyrene, 3,4-dimethylstyrene, 2-chlorostyrene,3-chlorostyrene, 4-chloro-3-methylstyrene, 3-tert-butylstyrene,2,4-dichlorostyrene, 2-,6-dichlorostyrene and 1-vinylnaphthalene. Asexamples of styrene polymers, mention may be made of polystyrene (PS),elastomer-modified PS, styrene/acrylonitrile (SAN) copolymers,elastomer-modified SAN, in particular ABS, which is obtained for exampleby grafting (graft polymerization) of styrene and acrylonitrile onto apolybutadiene or butadiene-acrylonitrile copolymer backbone, SAN/ABSblends, poly(alpha-methylstyrene) and polychlorostyrene.

The abovementioned elastomers may for example be EPR (the usualabbreviation for ethylene-propylene rubber or ethylene-propyleneelastomer), EPDM (the usual abbreviation for ethylene-propylene-dienemonomer rubber or ethylene-propylene-diene monomer elastomer),polybutadiene, acrylonitrile/butadiene copolymer, polyisoprene andisoprene/acrylonitrile copolymer.

The impact PS may be obtained (i) either by blending PS with elastomers,such as polybutadiene, butadiene/acrylonitrile copolymers, polyisopreneor isoprene/acrylonitrile copolymers (ii) or more usually by graftingstyrene (by graft polymerization) onto a polybutadiene orbutadiene/acrylonitrile copolymer backbone.

The styrene polymers also comprise the polymers listed above, some ofthe styrene monomer or monomers of which are replaced with unsaturatedmonomers that can be copolymerized with the styrene monomers, andespecially (meth)acrylic esters.

As examples of styrene copolymers, mention may be made ofstyrene/chlorostyrene copolymers, styrene/propylene copolymers,styrene/butadiene copolymers, styrene/isoprene copolymers, styrene/vinylchloride copolymers, styrene/vinyl acetate copolymers, styrene/alkylacrylate (methyl acrylate, ethyl acrylate, butyl acrylate, octylacrylate, phenyl acrylate, etc.) copolymers, styrene/alkyl methacrylate(methyl methacrylate, ethyl methacrylate, butyl methacrylate, octylmethacrylate, phenyl methacrylate, etc.) copolymers, styrene/methylchloroacrylate copolymers and styrene/acrylonitrile/alkyl(meth)acrylatecopolymers. In these copolymers, the comonomer(s) content will generallybe up to 20% by weight.

Among commercial polymers having vinylaromatic functional groups,mention may for example be made of FINAPRENE® (SBS &SBR), KRALON® (ABS),KRATON® (SBS & SEBS), LACORAN® (ABS), LACQRENE® (PS and impact-modifiedPS), LACQSAN® (SAN) and DYLARC® (SMA) (poly(styrene-co-maleic anhydride)with a low maleic anhydride content and poly(styrene-co-maleicanhydride) with a high maleic anhydride content).

Mention may also be made of functionalized polyolefins carrying at leastone carboxylic acid or carboxylic acid anhydride functional group.

The functionalized polyolefins may be unfunctionalized polyolefinpolymers with reactive units (the functionalities). The unfunctionalizedpolyolefins are conventionally homopolymers or copolymers ofalpha-olefins or of diolefins, such as for example ethylene, propylene,1-butene, 1-octene and butadiene. By way of examples, mention may bemade of:

-   -   ethylene homopolymers and copolymers, particularly LDPE, HDPE,        LLDPE (linear low-density polyethylene), VLDPE (very low-density        polyethylene) and metallocene polyethylene;    -   propylene homopolymers and copolymers;    -   ethylene/alpha-olefin copolymers such as ethylene/propylene        copolymers; EPRs (abbreviation for ethylene-propylene rubbers);        and ethylene/propylene/diene copolymers (EPDM);    -   styrene/ethylene-butylene/styrene block copolymers (SEBS),        styrene/butadiene/styrene block copolymers (SBS),        styrene/isoprene/styrene block copolymers (SIS),        styrene/ethylene-propylene/styrene block copolymers (SEPS);    -   copolymers of ethylene with at least one product chosen from        salts or esters of unsaturated carboxylic acids such as alkyl        (meth)acrylate (for example methyl acrylate), or vinyl esters of        saturated carboxylic acids such as vinyl acetate, the proportion        of comonomer(s) possibly being as much as 40% by weight;    -   blends of at least two of the abovementioned polyolefins, for        example a polypropylene blended with an EPR or EPDM copolymer,        it being possible for the latter to be optionally plasticized or        crosslinked during blending.

Advantageously, the unfunctionalized polyolefins are chosen frompropylene homopolymers or copolymers and any ethylene homopolymer orcopolymer and a comonomer of alpha-olefin type, such as propylene,butene, hexene, octene or 4-methyl-1-pentene. Mention may be made, forexample, of PP, high-density PE, medium-density PE, linear low-densityPE, low-density PE and very low-density PE. These polyethylenes areknown to those skilled in the art as being produced by a “radical”process, by “Ziegler”-type catalysis or, more recently, by so-called“metallocene” catalysis.

The unfunctionalized polyolefins may also be chosen from amorphouspoly(alpha-olefins) (APAOs). Preferably, APAOs derived from ethylene,propylene, butene or hexene are used. Advantageously, either ethylenepropylene butene copolymers with a high butene content, or ethylenepropylene butene copolymers with a high propylene content, or butenehomopolymers or copolymers are used.

The reactive units or functionalities are acid or anhydride functionalgroups. By way of example, mention may be made of the above polyolefinsgrafted or copolymerized or terpolymerized by carboxylic acids or thecorresponding salts or esters such as (meth)acrylic acid, or else bycarboxylic acid anhydrides such as maleic anhydride. A functionalizedpolyolefin is, for example, a PE/EPR blend, the weight ratio of whichmay vary between wide limits, for example between 40/60 and 90/10, thesaid blend being cografted with an anhydride, especially maleicanhydride, with a degree of grafting, for example, of 0.01 to 5% byweight.

The functionalized polyolefins may be chosen from the following(co)polymers, grafted with maleic anhydride, in which the degree ofgrafting is, for example, from 0.01 to 5% by weight:

-   -   PE, PP, copolymers of ethylene with propylene, butene, hexene,        or octene and containing, for example, from 35 to 80% by weight        of ethylene;    -   ethylene/alpha-olefin copolymers such as ethylene/propylene        copolymers; EPRs (abbreviation for ethylene-propylene rubbers);        and ethylene/propylene/diene copolymers (EPDM);    -   styrene/ethylene-butylene/styrene block copolymers (SEBS),        styrene/butadiene/styrene block copolymers (SBS),        styrene/isoprene/styrene block copolymers (SIS),        styrene/ethylene-propylene/styrene block copolymers (SEPS);    -   ethylene/vinyl acetate copolymers (EVA), containing up to 40% by        weight of vinyl acetate;    -   ethylene/alkyl (meth)acrylate copolymers, containing up to 40%        by weight of alkyl (meth)acrylate;    -   ethylene/vinyl acetate (EVA)/alkyl (meth)acrylate terpolymers,        containing up to 40% by weight of comonomers.

The functionalized polyolefin may also be a copolymer or terpolymer ofethylene and at least one of the following monomers: an alkyl(meth)acrylate or a vinyl ester of a saturated carboxylic acid and ananhydride such as maleic anhydride or (meth)acrylic acid.

By way of examples of functionalized polyolefins of this latter type,mention may be made of the following copolymers, in which the ethylenepreferably represents at least 60% by weight and in which the termonomer(the functional group) represents, for example, from 0.1 to 10% byweight of the copolymer:

-   -   ethylene/alkyl (meth)acrylate/(meth)acrylic acid or maleic        anhydride copolymers;    -   ethylene/vinyl acetate/maleic anhydride copolymers;    -   ethylene/vinyl acetate or alkyl (meth)acrylate/(meth)acrylic        acid or maleic anhydride copolymers.

In the foregoing, the term “alkyl (meth)acrylate” denotes C₁ to C₁₂alkyl methacrylates and acrylates, and may be chosen from methylacrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate,2-ethylhexyl acrylate, cyclohexyl acrylate, methyl methacrylate andethyl methacrylate.

The functionalized or unfunctionalized olefin copolymers mentioned abovemay be copolymerized so as to form random or block copolymers and mayhave a linear or branched structure.

The molar mass, the MFI index and the density of these polyolefins mayalso vary over a wide range, as those skilled in the art willappreciate. The MFI, the usual abbreviation for Melt Flow Index, ismeasured according to the ASTM 1238 standard.

Advantageously, the functionalized polyolefins are chosen from anypolymer comprising alpha-olefin units and units carrying polar reactivefunctional groups such as carboxylic acid or carboxylic acid anhydridefunctional groups. By way of examples of such polymers, mention may bemade of ethylene/alkyl acrylate/maleic anhydride terpolymers, such ascertain LOTADER® polymers sold by Arkema or maleic-anhydride-graftedpolyolefins such as certain OREVAC® polymers sold by Arkema, as well asethylene/alkyl acrylate/(meth)acrylic acid terpolymers or ethylene/vinylacetate/maleic anhydride terpolymers such as certain OREVAC® polymerssold by Arkema.

Mention may also be made of fluoropolymers corresponding to polymershaving, in their chain, at least one monomer chosen from compounds thatcontain a vinyl group capable of opening in order to be polymerized andthat contain, directly attached to this vinyl group, at least onefluorine atom, a fluoroalkyl group or a fluoroalkoxy group.

As examples of monomers, mention may be made of vinyl fluoride;vinylidene fluoride (VF2); trifluoroethylene (VF3);chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene;tetrafluoroethylene (TFE); hexafluoropropylene (HFP); perfluoro(alkylvinyl)ethers, such as perfluoro(methyl vinyl)ether (PMVE),perfluoro(ethyl vinyl)ether (PEVE) and perfluoro(propyl vinyl)ether(PPVE); perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole)(PDD); the product of formula CF₂═CFOCF₂CF(CF₃)OCF₂CF₂X in which X isSO₂F, CO₂H, CH₂OH, CH₂OCN or CH₂OPO₃H; the product of formulaCF₂═CFOCF₂CF₂SO₂F; the product of formula F(CF₂)_(n)CH₂OCF═CF₂ in whichn is 1, 2, 3, 4 or 5; the product of formula R₁CH₂OCF═CF₂ in which R₁ ishydrogen or F(CF₂)_(z) and z is 1, 2, 3 or 4; the product of formulaR₃OCF═CH₂ in which R₃ is F(CF₂)_(z)— and z is 1, 2, 3 or 4;perfluorobutylethylene (PFBE); 3,3,3-trifluoropropene and2-trifluoromethyl-3,3,3-trifluoro-1-propene.

Among the fluoropolymers listed above, vinylidene fluoride homopolymersand copolymers are preferred.

As examples of polymers falling within the compositions according to theinvention, mention may most particularly be made of LOTADER®, LOTRYL®,EVATANE®, ELVALLOY®, OREVAC®, PEBAX® and RILSAN®, sold by Arkema, andalso HYTREL®, sold by DuPont, and NORYL® polymers sold by GE Plastics,but also compounds filled with wood and/or lignine based on at least oneof these polymers and/or at least one polyolefin within the meaninggiven above.

The carbon nanotubes employed may be of any type: CNT, MWNT, SWNT,whether functionalized or not.

Preferably, the carbon nanotubes have a form factor (L/D) of 5 orhigher, and preferably 50 or higher and advantageously 100 or higher.

Advantageously, the carbon nanotubes have a diameter of between 0.4 and50 nm and a length of between 100 and 100 000 times their diameter.

According to a preferred embodiment of the invention, the carbonnanotubes are in the form of multiple-walled nanotubes (MWNTs), theirdiameter being between 5 and 30 nm and their length being 0.3 μm orhigher.

The quantity of carbon nanotubes advantageously represents 0.1 to 30parts by weight and advantageously 0.5 to 20 parts by weight of thetotal mass of the polymer material.

With regard to the B/C diblock, C may be obtained by the polymerizationof at least one monomer chosen from the group containing styrene andshort-chain methacrylates, such as methyl methacrylate. Preferably, Cconsists of methyl methacrylate monomers or contains at least 50% byweight of methyl methacrylate, preferably at least 75% by weight ofmethyl methacrylate. The other monomers constituting the block C may ormay not be acrylic monomers, and these may or may not be reactive. Theterm “reactive monomer” is understood to mean a chemical group capableof reacting with at least one of the functional groups of the polymer(s)or with the chemical groups of the hardener, if the polymer(s) is (are)of the thermosetting type and contains (contain) a hardener. Asnon-limiting examples of reactive functional groups, mention may be madeof oxirane functional groups, amine functional groups, an hydridefunctional groups and carboxylic acid functional groups. The reactivemonomer may be (meth)acrylic acid or any other hydrolyzable monomerresulting in these acids. Among the other monomers that may constitutethe block C, mention may be made by way of non-limiting example ofglycidyl (meth)acrylate and tert-butyl (meth)acrylate. Advantageously Cconsists of PMMA syndiotactic to at least 60%.

Advantageously the T_(g) of B is below 0° C. and preferably below −20°C.

The monomer used to synthesize the elastomeric block B may be a dienechosen from butadiene, isoprene, 2,3-dimethyl-1,3-butadiene,1,3-pentadiene and 2-phenyl-1,3-butadiene. Advantageously, B is chosenfrom polydienes, especially polybutadiene, polyisoprene and their randomcopolymers, or else from partially or completely hydrogenatedpolydienes. Among polybutadienes, it is advantageous to use those whoseT_(g) is the lowest, for example 1,4-polybutadiene with a T_(g) (ataround −90° C.) below that of 1,2-polybutadiene (around 0° C.). Theblocks B may also be hydrogenated. This hydrogenation is carried outusing standard techniques.

The monomer used to synthesize the elastomeric block B may also be analkyl (meth)acrylate, the following polymers being obtained with theT_(g) given in brackets after the name of the acrylate: ethyl acrylate(−24° C.), butyl acrylate (−54° C.), 2-ethylhexyl acrylate (−85° C.),hydroxyethyl acrylate (−15° C.) and 2-ethylhexyl methacrylate (−10° C.).Advantageously, butyl acrylate is used. The acrylates are different fromthose of the block C in order to satisfy the condition that B and C arenot miscible.

Preferably, the blocks B consist mostly of poly(1,4-butadiene).

The diblock B/C has a number-average molar mass that may be between 10000 g/mol and 500 000 g/mol, preferably between 20 000 and 200 000g/mol. Advantageously, the diblock B/C has a mass fraction C of between5 and 95% and preferably between 15 and 85%.

With regard to the triblock C/B/C, C is in general formed from the samemonomers and optionally copolymers as the block C of the diblock B/C.The two blocks C of the triblock C/B/C may be identical or different.They may also differ by their molar mass, but be formed from the samemonomers. The blocks C of the triblocks C/B/C may be identical ordifferent from the block C of the diblock B/C. The block B is formedfrom the same monomers and optionally comonomers as the block B of thediblock B/C. The blocks B of the triblock C/B/C and the diblock B/C maybe identical or different.

The triblock C/B/C has in general a number-average molar mass that maybe between 10 000 g/mol and 500 000 g/mol, preferably between 20 000 and200 000 g/mol. Advantageously, the triblock C/B/C has the followingcompositions in terms of C and B expressed as mass fractions, the totalbeing 100%:

-   -   C: between 10 and 80%, preferably between 15 and 70%;    -   B: between 90 and 20%, preferably between 85 and 30%.

With regard to the triblock A/B/C, C consists of the same monomers andoptionally comonomers as the block C of the diblock B/C. The block C ofthe triblock A/B/C, each block C of the triblock C/B/C, and the block Cof the diblock B/C may be identical or different. The block B consistsof the same monomers and optionally comonomers as the block B of thediblock B/C. The blocks B of the triblock A/B/C, of the triblock C/B/Cand of the diblock B/C may be identical or different.

The T_(g) or T_(m) of A is advantageously above 23° C. and preferablyabove 50° C. As examples of blocks A, mention may be made of those thatderive from vinylaromatic compounds, such as styrene, α-methyl styreneand vinyltoluene, and those that derive from alkyl esters of acrylicand/or methacrylic acids having 1 to 18 carbon atoms in the alkyl chain.In the latter case, the acrylates differ from those of the block C inorder to satisfy the condition that A and C are immiscible.

The triblock A/B/C has a number-average molar mass that may in generalbe between 10 000 g/mol and 500 000 g/mol, preferably between 20 000 and200 000 g/mol. Advantageously, the triblock A/B/C has the followingcomposition, expressed as fractions by weight, the total being 100%:

-   -   C: between 10 and 80%, preferably between 15 and 70%;    -   B: between 2 and 80%, preferably between 5 and 70%;    -   A: between 10 and 88%, preferably between 15 and 85%.

The blocks A may be manufactured by any polymerization means and inparticular by controlled radical polymerization. Controlled radicalpolymerization is known. Conventional radical polymerization techniquesdo not allow polymers and copolymers to be obtained with a controlledarchitecture, in particular because of the short lifetime of theradicals, their high reactivity and the lack of stereochemistry of theintermediate species. The expression “controlled radical polymerization”is understood to mean a conventional radical polymerization in which atleast one of the steps chosen from initiation, propagation, terminationand transfer is controlled. As an example of control, mention may bemade of the reversible deactivation of the growing macroradicals. Thisreversible deactivation may be brought about by the addition ofnitroxides into the reaction mixture. A persistent radical is forexample the TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) radical whichscavenges macroradicals and generally results in homopolymers of verylow polydispersivity, thus giving a living character to the radicalpolymerization. Mention may also be made of beta-phosphorylatedmolecules possessing a hydrogen in the alpha position of the nitroxidefunctional group.

The B/C, A/B/C and C/B/C block copolymers used as dispersing agents inthe polymer materials of the present invention may be manufactured byanionic polymerization, for example using the methods described inpatent applications EP 524 054 and EP 749 987, or by radicalpolymerization, and especially by controlled radical polymerization.

Advantageously, the proportion of dispersant is 1 to 35 parts by weightper 99 to 65 parts by weight of polymer(s) respectively.

Preferably, the proportion of dispersant is 8 to 32 parts by weight per92 to 68 parts by weight of polymer(s) respectively.

According to one particular embodiment of the invention, the dispersantincludes, in addition to one of the block copolymers C/B/C and A/B/C, atleast one polymer chosen from core-shell copolymers (E), functionalizedelastomers, A/B block copolymers and/or ATBN or CTBN reactive rubbers.

With regard to the diblock A/B, the blocks A and B are incompatible andare formed from the same monomers and possibly comonomers as the blocksA and the blocks B of the triblock A/B/C. The blocks A and B may beidentical or different from the other blocks A and B present in theother block copolymers of the impact modifier in the thermosettingmaterial.

The diblock A/B generally has a number-average molar mass that may bebetween 10 000 g/mol and 500 000 g/mol, preferably between 20 000 and200 000 g/mol. Advantageously, the diblock A/B has a mass fraction of Bof between 5 and 95%, preferably between 15 and 85%.

With regard to the core-shell copolymer (E), this is in the form of fineparticles having an elastomer core and at least one thermoplastic shell,the particle size being generally less than 1 μm and advantageouslybetween 50 and 500 nm. By way of example of the core, mention may bemade of isoprene homopolymers or butadiene homopolymers, copolymers ofisoprene with at most 30 mol % of a vinyl monomer and copolymers ofbutadiene with at most 30 mol % of a vinyl monomer. The vinyl monomermay be styrene, an alkylstyrene, acrylonitrile or an alkyl(meth)acrylate. Another core family consists of the homopolymers of analkyl (meth)acrylate and the copolymers of an alkyl (meth)acrylate withat most 30 mol % of a vinyl monomer. The alkyl (meth)acrylate isadvantageously butyl acrylate. The vinyl monomer may be styrene, analkylstyrene, acrylonitrile, butadiene or isoprene. The core of thecopolymer (A) may be completely or partly crosslinked. All that isrequired is to add at least difunctional monomers during the preparationof the core; these monomers may be chosen from poly(meth)acrylic estersof polyols, such as butylene di(meth)acrylate and trimethylolpropanetrimethacrylate. Other difunctional monomers are, for example,divinylbenzene, trivinylbenzene, vinyl acrylate and vinyl methacrylate.The core can also be crosslinked by introducing into it, by grafting oras a comonomer during the polymerization, unsaturated functionalmonomers such as anhydrides of unsaturated carboxylic acids, unsaturatedcarboxylic acids and unsaturated epoxides. Mention may be made, by wayof example, of maleic anhydride, (meth)acrylic acid and glycidylmethacrylate.

The shell(s) are styrene homopolymers, alkylstyrene homopolymers ormethyl methacrylate homopolymers, or copolymers comprising at least 70mol % of one of the above monomers and at least one comonomer chosenfrom the other above monomers, vinyl acetate and acrylonitrile. Theshell may be functionalized by introducing into it, by grafting or as acomonomer during the polymerization, unsaturated functional monomerssuch as anhydrides of unsaturated carboxylic acids, unsaturatedcarboxylic acids and unsaturated epoxides. Mention may be made, forexample, of maleic anhydride, (meth)acrylic acid and glycidylmethacrylate. By way of example, mention may be made of core-shellcopolymers (E) having a polystyrene shell and core-shell copolymers (E)having a PMMA shell. There are also core-shell copolymers (E) having twoshells, one made of polystyrene and the other, on the outside, made ofPMMA. Examples of copolymers (E) and their method of preparation aredescribed in the following patents: U.S. Pat. No. 4,180,494, U.S. Pat.No. 3,808,180, U.S. Pat. No. 4,096,202, U.S. Pat. No. 4,260,693, U.S.Pat. No. 3,287,443, U.S. Pat. No. 3,657,391, U.S. Pat. No. 4,299,928 andU.S. Pat. No. 3,985,704.

Advantageously, the core represents, by weight, 70 to 90% of (A) and theshell represents 30 to 10%.

By way of example of a copolymer (E), mention may be made of thatconsisting (i) of 75 to 80 parts of a core comprising at least 93 mol %of butadiene, 5 mol % of styrene and 0.5 to 1 mol % of divinylbenzeneand (ii) of 25 to 20 parts of two shells essentially of the same weight,the inner one made of polystyrene and the outer one made of PMMA.

According to a second particular embodiment of the invention, thedispersant comprises at least one A/B/C block copolymer and at least oneA/B block copolymer. The impact modifier advantageously comprisesbetween 5 and 80% of the diblock A/B per 95 to 20% of the triblockA/B/C.

Moreover, the advantage of these compositions is that it is unnecessaryto purify the A/B/C after its synthesis. This is because the A/B/Ctriblocks are in general prepared from A/B diblocks, and the reactionoften leads to a blend of A/B and A/B/C, which can then be separated inorder to have S/B/M.

According to a third particular embodiment of the invention, thedispersant comprises at least one A/B/C block copolymer and at least onecore-shell copolymer (E). The proportion of core-shell copolymerrelative to A/B/C may be between 5 and 1 per 1 and 4, preferably between3 and 1 per 1 and 2.

According to a fourth particular embodiment of the invention, thedispersant comprises at least one A/B/C block copolymer and at least oneATBN or CTBN reactive rubber. The proportion of reactive rubber relativeto A/B/C may be between 5 and 1 per 1 and 4, and preferably between 3and 1 per 1 and 2.

ATBN and CTBN are the respective abbreviations for:

-   -   CTBN: carboxyl-terminated random butadiene/acrylonitrile        copolymer;    -   ATBN: amino-terminated random butadiene/acrylonitrile copolymer.

These products are oligomers based on butadiene and acrylonitrile andare terminated either by carboxyl functional groups or by aminefunctional groups. Butadiene has a very low T_(g), this being favourablefor obtaining good impact reinforcement.

According to one advantageous embodiment, part of the A/B/C triblock maybe replaced with an A/B diblock. This part may be up to 70% by weight ofthe A/B/C triblock.

It would not be outside the scope of the invention to replace all orpart of the A/B/C triblock with a C/A/B/A/C or C/B/A/B/C pentablock.They may be prepared by anionic polymerization, like the abovementioneddiblocks or triblocks, but using a difunctional initiator. Thenumber-average molar mass of these pentablocks lies within the samerange as that of the A/B/C triblocks. The proportion of the two blocks Ctogether or of the two blocks B or A together lies within the same rangeas the proportions of A, B and C in the A/B/C triblock.

Dispersants Particularly Preferred by the Applicant

ABC1: this is an A/B/C triblock copolymer in which A is polystyrene, Bis polybutadiene and C is PMMA containing 22 wt % polystyrene, 9 wt %polybutadiene and 69 wt % polymethyl methacrylate, obtained by anionicpolymerization in succession of a polystyrene block of 27 000 g/molnumber-average molar mass, of a polybutadiene block of 11 000 g/mol massand of a polymethyl methacrylate block of 84 000 g/mol number-averagemolar mass. This product was prepared according to the operating methoddescribed in EP 524 054 and in EP 749 987. This product has three glasstransitions, one at −90° C., another at 95° C. and the third at 130° C.

ABC2: this is an A/B/C triblock copolymer in which A is polystyrene, Bis polybutadiene and C is PMMA containing 12 wt % polystyrene, 18 wt %polybutadiene and 70 wt % polymethyl methacrylate, obtained by anionicpolymerization in succession of a polystyrene block of 14 000 g/molnumber-average molar mass, of a polybutadiene block of 22 000 g/mol massand of a polymethyl methacrylate block of 85 000 g/mol number-averagemolar mass. This product was prepared according to the operating methoddescribed in EP 524 054 and in EP 749 987. This product has three glasstransitions, one at −90° C., another at 95° C. and the third at 130° C.

ABC3: this is an A/B/C triblock copolymer in which A is polystyrene, Bis polybutadiene and C is PMMA containing 24 wt % polystyrene, 26 wt %polybutadiene and 50 wt % polymethyl methacrylate, obtained by anionicpolymerization in succession of a polystyrene block of 21 000 g/molnumber-average molar mass, of a polybutadiene block of 22 000 g/mol massand of a polymethyl methacrylate block of 43 000 g/mol number-averagemolar mass. This product was prepared according to the operating methoddescribed in EP 524 054 and in EP 749 987. This product has three glasstransitions, one at −90° C., another at 95° C. and the third at 130° C.

ABC4: this is an A/B/C triblock copolymer in which the blocks A and Care identical, both being PMMA, and the block B is a butyl acrylatehomopolymer. This polymer is obtained by controlled radicalpolymerization. The number-average molar mass of butyl acrylate is 22000 g/mol and the weight-average molar mass of the total copolymer is140 000 g/mol.

ABC5: this is an A/B/C triblock copolymer in which the blocks A and Care identical, both being methyl methacrylate (MMA)/dimethylacrylamide(DMA) copolymers, and the block B is a butyl acrylate homopolymer.

As examples:

-   -   for polymer materials based on PA, PPE/PA, PS, ABS, PMMA and PC,        the dispersants of ABC1 to ABC3 type are particularly preferred        by the Applicant;    -   for epoxy-based polymer materials, the dispersants of ABC1 to        ABC5 type are particularly preferred by the Applicant; and    -   for PVDF-based polymer materials, the dispersants of ABC1 to        ABC3 or ABC4 type are particularly preferred by the Applicant.

The mixing method may use various technologies, such as those used forrubbers, polymers and liquids, depending on the nature of the polymerspresent in the final compound. Mention may be made of internal mixers,single-screw or twin-screw extruders, Buss co-kneaders, Ultraturax-typemixers, ultrasonic mixers or any type of mixing tool known to thoseskilled in the art.

The compositions described above may be obtained directly by mixing oneor more polymer materials, one or more dispersants and CNTs or bydilution via the use of a masterbatch as described in WO 91/03057 orU.S. Pat. No. 5,646,990, EP 692 136 or U.S. Pat. No. 5,591,382, U.S.Pat. No. 5,643,502 or U.S. Pat. No. 5,651,922 and U.S. Pat. No.6,221,283.

The masterbatches may be formed from CNTs and one or more dispersants,or else they may contain a certain amount of polymer material, thedilution resin not necessarily being the same as that used in thecomposition of the masterbatch.

In the case of thermosetting polymer materials, depending on the amountof dispersant used, it is possible to reproduce the operating conditionsdescribed in WO 91/01 92415 by simply adding the CNTs into the reactionmixture.

The thermosetting materials according to the invention with a lowpercentage of dispersant(s) (<10 parts by weight) may be prepared usinga conventional stirred reactor. The thermosetting polymer is introducedinto the reactor and heated for a few minutes at a temperaturesufficient for it to be fluid. The dispersant, comprising the blockcopolymer(s) is then added and mixed at a temperature sufficient for itto be fluid, until it has completely dissolved. The mixing time dependson the nature of the copolymer added. The hardener is then added andmixed for a further 5 minutes at a temperature sufficient for it to befluid, in order to obtain a uniform compound. The epoxy-hardenerreaction starts during this compounding, and it must therefore be set asshort as possible. These compounds are then cast into a mould and cured.

For thermosetting materials with a dispersant content of greater than 10parts by weight, a premix consisting of the thermosetting resin and thedispersant containing about 10% by mass of impact modifier is producedusing the following method: after having heated the thermosettingpolymer at a temperature sufficient for it to be fluid for a fewminutes, the dispersant is added and mixed at a temperature sufficientfor it to be fluid, until it has completely dissolved. The mass ofdispersant that remains in order to achieve the desired content is thenmixed to this premix using for example a calender or a twin-screw mixerat a temperature sufficient for it to be fluid for one hour. Thethermosetting resin/impact dispersant system obtained is then cooled andcryogenically ground, and the hardener is added. The final compound ispressed in a mould at the desired cure temperature.

The polymer materials according to the invention may advantageouslyreplace the polymer materials containing CNTs of the prior art and beused in many fields, especially in electronics (they may be conductors,semiconductors or insulators depending on the temperature and theirstructure), in mechanical systems, for example for reinforcingcomposites (CNTs are one hundred times stronger and six times lighterthan steel) and in electromechanical systems (they may expand orcontract by injecting charge). For example, mention may be made ofmaterials intended for example for the packaging of electroniccomponents, for the manufacture of fuel lines, antistatic coatings, inthermistors, electrodes for supercapacitors, etc.

EXAMPLES

The following products were used:

Epoxy polymer: this was a diglycidyl ether of bisphenol A (DGEBA) of 383g/mol molar mass with an average hydroxyl group number per one epoxygroup of n=0.075, sold by Ciba-Geigy under the brand name LY556.

Hardener: this was an amine hardener, namely the aromatic diamine4,4′-methylenebis(3-chloro-2,6-diethylaniline) sold by Lonza under thebrand name LONZACURE M-CDEA. This product is characterized by a meltingpoint of between 87° C. and 90° C. and a molar mass of 380 g/mol.

Particle dispersant: this was an A/B/C triblock copolymer of the ABC3type.

Carbon particles: carbon nanotubes obtained according to the methoddescribed in WO 03/002456 A2 were used. These nanotubes had a diameterof between 10 and 30 nm and a length of greater than 0.4 μm. They wereof the multi-walled (MW) type, not purified and not functionalized andrepresented in total or by more than 98% in separated form, that is tosay not aggregated.

Preparation of the compounds: 2 g of DGEBA were heated at 135° C., and,after liquefaction, 440 mg of ABC3 triblock were added and left, withstirring, at 135° C. for 3 h. Next, 44 mg of CNT were added and stirringmaintained at temperature for 12 h. Next, 2 g of MCDEA hardener wereadded and stirring applied for 5 min at 135° C. The compound was thencast into a mould and cured for 5 hours at 135° C.

1. Polymer material comprising: 99 to 20 parts by weight of polymers;0.1 to 80 parts by weight of carbon nanotubes; and 0.05 to 80 parts byweight of at least one dispersant selected from A/B/C, B/C, C/B/C blockcopolymers or mixtures thereof in which: each block is linked to anotherby means of a covalent bond or an intermediate molecule linked to one ofthe blocks via a covalent bond and to the other block via anothercovalent bond, C provides an interaction of the chemical and/or physicaltype with the polymer material, B is not miscible with the polymermaterial and with the block C, and its glass transition temperatureT_(g) is below the usage temperature of the polymer material and A isnot miscible with the polymer material, the block B and the block C, andits T_(g) or its melting point T_(m) is above the T_(g) of B. 2.Material according to claim 1, in which the blocks C of the blockcopolymers are formed from PMMA syndiotactic to at least 60%. 3.Material according to claim 1, in which the blocks C of the blockcopolymers comprise reactive monomers.
 4. Material according to claim 1,in which the T_(g) of the blocks B of the block copolymers is below 0°C.
 5. Material according to claim 4, in which the blocks B of the blockcopolymers comprise 1,4-polybutadiene.
 6. Material according to claim 5,in which the dienes of the block B are hydrogenated.
 7. Materialaccording to claim 4, in which the block B consists of polybutylacrylate.
 8. Material according to claim 1, in which the T_(g) or theT_(m) of the blocks A is above 23° C.
 9. Material according to claim 8,in which A is polystyrene.
 10. Material according to claim 1, in whichthe number-average molar mass of the dispersant is between 10 000 g/moland 500 000 g/mol.
 11. Material according to claim 1, in which theproportion of dispersant(s) is 1 to 35% per 99 to 65% of polymerrespectively.
 12. Material according to claim 1, in which the proportionof carbon nanotubes represents 0.1 to 30 parts by weight of the totalmass of the polymer material.
 13. Material according to claim 1, inwhich the dispersant comprises at least one of the C/B/C or A/B/C blockcopolymers and at least one polymer selected from: core-shell copolymers(E), functionalized elastomers, A/B block copolymers, ATBN or CTBNreactive rubbers.
 14. Material according to claim 13, in which thedispersant includes at least one A/B/C block copolymer and at least oneA/B block copolymer and/or at least one core-shell copolymer (E) and/orat least one ATBN or CTBN reactive rubbers and optionally an A/B blockcopolymer.
 15. Material according to claim 1, in which all or part ofthe A/B/C triblock is replaced with a C/A/B/A/C and/or C/B/A/B/Cpentablock.
 16. Material according to claim 1, in which the polymer isselected from PA, PPE/PA, PS, ABS, PMMA, PC, epoxy-based polymers orPVDF-based polymers.
 17. Material according to claim 1, in which C ismiscible with said material.
 18. Material according to claim 3, in whichsaid reactive monomer is selected from glycidyl (meth)acrylate,tert-butyl(meth)acrylate or mixtures thereof.
 19. Material according toclaim 4, in which the T_(g) of the blocks B of the block copolymers isbelow −20° C.
 20. Material according to claim 1, in which the T_(g) orthe T_(m) of the blocks A is above 50° C.
 21. Material according toclaim 1, in which the number-average molar mass of the dispersant isbetween 20 000 g/mol and 200 000 g/mol.
 22. Material according to claim1, in which the proportion of carbon nanotubes represents 0.5 to 20parts by weight of the total mass of the polymer material.
 23. Materialaccording to claim 13, in which the carbon nanotubes comprisemulti-walled nanotubes (MWNT) having a diameter being between 5 and 30nm and their length being 0.3 μm or higher.
 24. Material according toclaim 13, in which the blocks A have a number-average molar mass between10 000 g/mol and 500 000 g/mol.